Displaying a sequence of still images is used for many purposes, like performing a slideshow, viewing a collection of photographs or to have something interesting to look at when a computer is locked (screensaver). A sequence of static images however does not always capture the attention of the viewer. To combat this and to make a sequence of still images more attractive, techniques such as zooming in or out and scrolling from one part of the image to another are often used to give the impression of motion. One of the prior art techniques was made famous by Ken Burns, and it is often referred to as the Ken Burns Effect. The Ken Burns Effect is well known among those skilled in the art (see e.g. description on Wikipedia). It is a technique of embedding still photographs in motion pictures, displayed with slow zooming and panning effects, and fading transitions between them. It can be used to give the impression of animation to still pictures by e.g. slowly zooming in on subjects of interest and then moving from one subject to another. For example, in a photograph with several persons, the focus might slowly pan across the faces and come to rest on one person. With focus it is intended that the center (or an emphasized part) of the image is displayed.
The Ken Burns effect can be used as a transition between clips as well. For example, to segue from one person in the story to another, an operator might open a clip with a close-up of one person in a photo, then zoom out so that another person in the photo becomes visible. This is especially practicable when covering older subjects where there is little or no available film. The zooming and panning across photographs gives the feeling of motion, and keeps the viewer visually entertained. This technique has become a staple of documentaries, slide shows, presentations, and even screen savers. Existing editing systems, some of which also use this effect for screensavers, often include the Ken Burns Effect or transition, with which a still image may be incorporated into a film using this kind of slow pan and zoom. Some picture slideshow systems or photo editing programs present such an option labelled “Ken Burns Effect”.
The Ken Burns effect is customizable and can be applied together with other effects using code like the one described in the following page: http://forums.slideshowpro.net/viewtopic.php?pid=29056
The Ken Burns effect works very well when applied manually to each image, but all current attempts to apply the effect automatically (like in iPhoto screenshows) are less effective as the program that applies the technique does not know what is the subject of the image, and cannot therefore apply the most appropriate effect. Often the result can be unpleasant, as it excludes all or part of the interesting portions of the image. To combat this, some programs minimize the impact of the animation, by ensuring that very little of the area of the image is ever excluded from the view, but this reduces the positive effects.
It is an object of the present invention to provide a technique which alleviates the above drawback of the prior art.